Bandwidth on-demand services in multiple layer networks

ABSTRACT

Bandwidth usage for an existing communication tunnel between a first device and second device is monitored. A determination is made that additional bandwidth is required for communication between the first network device and the second network device. A determination is made that for the addition of the additional bandwidth would exceed available bandwidth for the existing tunnel. Additional bandwidth is established between the first network device and the second network device.

PRIORITY CLAIM

The subject patent application is a continuation of U.S. Non-Provisionalapplication Ser. No. 13/957,533, filed Aug. 2, 2013, which in turnclaims the benefit of U.S. Provisional Application No. 61/729,119, filedNov. 21, 2012, the entireties of which are hereby incorporated byreference.

TECHNICAL FIELD

The present disclosure relates to computer networks, and in particular,multilayer computer networks.

BACKGROUND

Network infrastructures may employ multiple layer networks. For example,a network may comprise both an Internet Protocol (IP) network layer, aswell as an optical network layer. Often, the separate network layerswill exhibit different bandwidth availability at a particular time andfor a particular application.

Multiprotocol Label Switching (MPLS) is a mechanism in high-performancenetworks that directs data from one network node to the next based onshort path labels rather than long network addresses, avoiding complexlookups in a routing table. The labels identify virtual links (paths)between distant nodes rather than endpoints. MPLS can encapsulatepackets of various network protocols. The Generalized Multi-ProtocolLabel Switching (GMPLS) is a protocol suite extending MPLS to managefurther classes of interfaces and switching technologies other thanpacket interfaces and switching, such as time division multiplex,layer-2 switch, wavelength switch and fiber-switch.

A path computation element (PCE) is a system component, application, ornetwork node that is capable of determining and finding a suitable routefor conveying data between a source and a destination. In MPLS and GMPLSnetworks, the PCE is used to determine the path through the network thattraffic should follow, and provides the route for each Label Switch Path(LSP) that is set up. A PCE might be a network node, network managementstation, or dedicated computational platform that is resource-aware andhas the ability to consider multiple constraints for sophisticated pathcomputation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a network environment configured to provide bandwidthon demand services in a network having multiple layers.

FIG. 2 is a flowchart illustrating a process for providing bandwidthon-demand services.

FIG. 3 illustrates an example network environment and the accompanyingnetwork processes utilized in providing bandwidth on-demand services.

FIG. 4 illustrates a second example network environment and theaccompanying network processes utilized in providing bandwidth on-demandservices.

FIG. 5 illustrates a third example network environment and theaccompanying network processes utilized in providing bandwidth on-demandservices.

FIG. 6 is a block diagram of a network device configured to providebandwidth on-demand services.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Overview

Bandwidth usage for an existing communication tunnel between a firstdevice and second device is monitored. A determination is made thatadditional bandwidth is required for communication between the firstnetwork device and the second network device is received. Adetermination is made that the addition of the additional bandwidthwould exceed available bandwidth for the existing tunnel. Additionalbandwidth is established between the first network device and the secondnetwork device.

Example Embodiments

With reference made to FIG. 1, depicted therein is a network environment100 comprising a first network layer 105 and a second network layer 110which are in communication with each other through network layerinterfaces 115 a-c. Other example networks may include three or morenetwork layers.

According to example network environment 100, the first network layer105 may be an Open System Interconnection (OSI) model layer 3 networksuch as an internet protocol (IP), or packet network. First networklayer 105 includes multiple routers 120 a-e interconnected throughnetwork links 122 a-d. The second network layer 110 may be an opticalnetwork which resides at the OSI layer 0, and includes multiple opticalnodes 125 a-c interconnected through optical links 127 a-c. Accordingly,the routers 120 a-e can intercommunicate, as can optical nodes 125 a-c.Furthermore, the first network layer 105 routers 120 a-e can communicatewith the second network layer 110 optical nodes 125 a-c through networklayer interfaces 115 a-c.

While a layer 3 network layer is combined with an optical network layerin network environment 100, other example network environments are notlimited to specific OSI layers, or network technology. For example,other example network environments may comprise OSI layer-2 networkscombined with IP or layer 3 networks.

Also illustrated in FIG. 1 is stateful network device 130. According tothe specific example of FIG. 1, network device 130 is a stateful pathcomputation element (PCE). As used herein “stateful” refers to a devicethat is capable of tracking activity in a network, such as one or bothof network layers 150 and 110. A stateful device not only tracks theamount of traffic in a network, but also tracks the source anddestination of the traffic. Accordingly, if router 120 a iscommunicating with router 120 b through router 120 d, stateful PCE 130would be “aware” of the amount of traffic between routers 120 a and 120b, the source and destination of the traffic, and the path for thetraffic. While a single PCE 130 is illustrated in FIG. 1, the techniquesdescribed herein may be implemented in multiple cooperating PCEs.

Included in PCE 130 is bandwidth on-demand functional unit 135, which isconfigured to provide on-demand bandwidth for communications between oneor more of routers 120 a-e and optical nodes 125 a-c. For example, twoof routers 120 a-e may be communicating through a communication tunnelpassing through one or more network links 122 a-d. Additional bandwidthfor the communication may be required that exceeds the abilities of themaximum bandwidth of the current communication tunnel. Bandwidth ondemand functional unit 135 is configured to provide additional,on-demand bandwidth as described below in reference to FIGS. 2-5.

With reference now made to FIG. 2, depicted therein is a flowchart 200illustrating a process for providing on-demand bandwidth between two ormore network devices. The process begins in 205 where bandwidth usagefor an existing communication tunnel between a first network device anda second network device is monitored. The monitoring may take place, forexample, at a stateful network device, such as a PCE. A stateful PCE isconfigured to monitor current network communication tunnels. Anon-stateful PCE, on the other hand, will simply calculate a networkpath in response to a request without any further monitoring of thecommunications.

In 210, a determination is made that additional bandwidth is requiredfor communication between the network device and the second networkdevice. According to one example, and as described below with referenceto FIGS. 3-5, a request for additional bandwidth for communicationbetween the first network device and the second network device may bereceived at a PCE. According to other examples, a stateful PCE will beable to determine when additional bandwidth is needed based on itsmonitoring of the communications between the first device and seconddevice. In other words, the stateful PCE may trigger the addition ofbandwidth, as described below with reference to blocks 215 and 220,without relying on receipt of an outside request.

In 215, a determination is made that the addition of the additionalbandwidth would exceed the available bandwidth in the existingcommunication tunnel. For example, if a communication tunnel is using 7gigabytes of bandwidth over 10 gigabyte network links, a request for anadditional 8 gigabytes of bandwidth could not be fulfilled over theestablished communication tunnel. Remaining with the example of thestateful PCE, because the stateful PCE monitors the communicationsbetween the two network devices, it can perform the calculationsnecessary to determine whether or not the current communication tunnelis capable of providing the requested bandwidth. A non-stateful PCE, onthe other hand, would not be aware that the existing tunnel is in use,much less, the current bandwidth utilization of the existing tunnel.Accordingly, a non-stateful PCE could not easily determine whether ornot the request for additional bandwidth could be met by the networklinks utilized by the existing tunnel.

According to other examples, the established communication tunnel maycommunicate through networks links which can handle additionalbandwidth, even though the bandwidth allocation for the establishedcommunication tunnel is less than the bandwidth needed for thecommunications between the first device and the second device. Astateful PCE may determine that the bandwidth necessary forcommunication exceeds the bandwidth allocation for the existingcommunication tunnel.

Finally, in 220, additional bandwidth is established between the firstnetwork device and the second network device. For example, an additionalcommunication tunnel may be established between the first device and thesecond device in order to fulfill the bandwidth request received in 210.The additional communication tunnel may span two or more network layers,as shall be described below in reference to FIGS. 3-5. According toother examples, the bandwidth allocation for the existing communicationtunnel may be expanded.

Turning now to FIG. 3, depicted therein is an illustration of providingadditional bandwidth through an additional communication tunnel whichspans more than one network layer. As illustrated, a network environmentsimilar to that of FIG. 1 is depicted, and therefore, like referencenumerals have been used to refer to like elements.

Initially in FIG. 3, an existing communication tunnel 305 has beenestablished between router 120 a and router 120 b. Specifically,existing tunnel 305 comprises network link 122 a, router 120 d andnetwork link 122 c. According to the example of FIG. 3, each networklink 122 a-d is a 10 gigabyte link. Accordingly, if the communicationsbetween router 120 a and 120 b require 7 gigabytes of bandwidth,communication tunnel 305 is sufficient to handle the bandwidthrequirements.

PCE 130 monitors the communications over communication tunnel 305 untilbandwidth request message 310 is received by PCE 130 from router 120 a.If request message 310 is a message requesting an additional 2 gigabytesof bandwidth, PCE 130 may respond by expanding existing communicationtunnel 305. Specifically, because links 122 a and 112 b are 10 gigabytelinks, and a total of 9 gigabytes is needed (the existing 7 gigabytesplus the additional 2 gigabytes), PCE may be to determine that existingcommunication tunnel may be expanded to accommodate the additionallyrequested bandwidth. On the other hand, if request message 310 requestsan additional 8 gigabytes of bandwidth for communication between router120 a and router 120 b, network links 122 a and 122 b are incapable ofsupporting a total bandwidth of 15 gigabytes.

Because PCE 130 is stateful, and has been monitoring existing tunnel305, PCE 130, and bandwidth on demand functional unit 135 in particular,is aware that tunnel 305 is incapable of fulfilling the request for anadditional 7 gigabytes of bandwidth as requested in request message 310.Accordingly, bandwidth on demand functional unit 135 will send message315 to router 120 a, providing a path for an additional communicationtunnel 325 through second network layer 110.

If PCE 130 is aware of the topology of both first network layer 105 andsecond network layer 110, message 315 sent by bandwidth on-demandfunctional unit 135 may explicitly define the entire path from router120 a to router 120 b through the second network layer 110. For example,if router 120 a and router 120 b communicate according to a labelswitched path (LSP) protocol, such as Multiprotocol Label Switching(MPLS) or Generalized Multiprotocol Label Switching (GMPLS), and PCE 130is aware of the topology of second network layer 110, message 315 mayinclude the entire LSP from router 120 a to 120 b. Specifically, message315 may explicitly define the path for tunnel 325 which includes networklayer interface 115 a, optical node 125 a, optical path 127 a, opticalnode 125 b, and network layer interface 115 b. Upon receiving message315, router 120 a may establish a circuit for tunnel 325, and begincommunicating through communication tunnel 325. Message 315 may take theform of an LSP “Create” message sent according to the Path ComputationElement Protocol (PCEP). Specifically, message 315 may include anexplicit route object (ERO) defining the path from router 120 a torouter 120 b.

In order to establish tunnel 325, router 120 a may first send the LSPdata to router 120 b, thereby establishing a circuit for tunnel 325. Thesending of the LSP information to router 120 b may take the form of aResource Reservation Protocol-Traffic Engineering (RSVP-TE) message. AnRSVP-TE generally allows for the establishment of MPLS LSPs, taking intoconsideration network constraint parameters such as available bandwidthand explicit hops.

According to another example, the creation of tunnel 325 includes PCE130 sending message 320 to router 120 b in addition to sending message315 to router 120 a. Each of messages 315 and 320 include the LSPinformation necessary to establish tunnel 325 for a bi-directional GMPLSLSP.

When the establishment of bandwidth on demand communication tunnel 325is implemented in a GMPLS environment, the techniques herein may extendthe PCEP LSP Create Message with the LSP_TUNNEL_INTERFACE_ID Object.Specifically, the LSP_TUNNEL_INTERFACE_ID Object is configured tocommunicate LSP provisioning information from the ingress node (router120 a) to the egress node (router 120 b).

When the single sided provisioning model is used (i.e. only message 315is sent from PCE 130, and message 320 is not utilized) in which RSVP-TEsignaling is implemented, an LSP Request Message with anLSP_TUNNEL_INTERFACE_ID object in the RSVP TE Path message is sent fromrouter 120 a to router 120 b.

Once new communication tunnel 325 is established, PCE 130 will continueto monitor the communications between routers 120 a and 120 b. If thebandwidth requirements for the communications change, PCE 130 maydynamically alter one or more of the communication tunnels betweenrouters 120 a and 120 b. For example, if the bandwidth demands remainabove 10 gigabytes, but less than the 15 gigabytes currently reservedbetween tunnels 305 and 325, one or both of tunnels 305 and 325 may bereduced in size. Similarly, if the required bandwidth for thecommunications between router 120 a and 120 b drop below 10 gigabytes,the size of communication tunnels 305 and 325 may be altered, includingthe elimination of one of the tunnels. For example, if the bandwidthrequirement for the communications between routers 120 a and 120 b isdetermined to be 9 gigabytes, communication tunnel 305 may be expandedto handle 9 gigabytes of bandwidth, and communication tunnel 325 may beeliminated. On the other hand, PCE 130 may accommodate the change bysimply reducing the bandwidth allocation for tunnel 325 to 2 gigabyteswithout making any changes to the bandwidth allocation for tunnel 305.Similarly, PCE 130 may accommodate the change by simply reducing thebandwidth allocation for tunnel 305 to 1 gigabyte without making anychanges to the bandwidth allocation for tunnel 325.

With reference now made to FIG. 4, unlike the example of FIG. 3, PCE 130may only be aware of the topology of first network layer 105. Forexample, PCE 130 may be aware that network layer interfaces 115 a-c allconnect to second network later 110, but PCE 130 is unaware of theunderlying structure of second network layer 110. Specifically, PCE 130would not be aware of the structure and arrangement of optical nodes 125a-c and optical links 127 a-c.

PCE 130 may have partial awareness of network layer interfaces throughsignaling provided by routers 120 a-c, the routers connected to thesecond network layer 110 through network layer interfaces 115 a-c.Specifically, PCE 130 may be receiving minimal reachability informationfor the optical network. In particular, PCE 130 may learn the opticaladdresses associated with routers 120 a-c through one or more means. Forexample, routers 120 a-c may advertise or flood network layer 105 withmessages indicating that routers 120 a-c have virtual interconnectivity.These signaling messages may include the optical addresses for routers120 a-c. According to other examples, the optical addresses for routers120 a-c may be tagged addresses in an intermediate to intermediatesystem (ISIS) network. In additional examples, the optical addresses forrouters 120 a-c may be flooded to first network layer 105 as stabs in anOpen Shortest Path First (OSPF) environment.

Accordingly, while the process of establishing on-demand bandwidthbegins in a manner similar to that of FIG. 3, because PCE 130 is notaware of the full topology of second network layer 110, thedetermination of the path through second network layer 110 isaccomplished through different means.

As with the example of FIG. 3, each network link 122 a-d in FIG. 4 is a10 gigabyte link. Accordingly, if the communications between router 120a and 120 b require 7 gigabytes of bandwidth, communication tunnel 305is sufficient to handle the bandwidth requirements.

PCE 130 monitors the communications over communication tunnel 305 untilbandwidth request message 310 is received by PCE 130 from router 120 a.Request message 310 requests an additional 8 gigabytes of bandwidth forcommunication between router 120 a and router 120 b. Just as describedabove in reference to FIG. 3, network links 122 a and 122 b of FIG. 4are only 10 gigabyte links, and therefore, are incapable of supporting atotal bandwidth of 15 gigabytes. Because PCE 130 is stateful, and hasbeen monitoring existing tunnel 305, PCE 130, and bandwidth on-demandfunctional unit 135 in particular, is aware that tunnel 305 is incapableof fulfilling the request in message 310.

In response to message 310, bandwidth on demand functional unit 135 willsend message 415 to router 120 a. But, unlike message 315 of FIG. 3,message 415 does not define an explicit path through second networklayer 110. Instead, message 415 will include second network layer 110addresses for router 120 a and router 120 b. Specifically, becauserouter 120 a and router 120 b are connected to the second network layer110 through network layer interface 115 a and network layer interface 11b, respectively, routers 120 a and 120 b will have a second networklayer 110 address, or an optical address, associated with them.

Upon receipt of message 415, in order to determine the path throughsecond network layer 110, router 120 a may attempt to establish asuccessful path through a trial-and-error process. Specifically, router120 a may send message 420 to optical node 125 a, which also includesthe optical addresses for router 120 a and router 120 b. Upon receivingmessage 420, optical node 125 a can complete the path for the additionalcommunication through, for example, signaling over the second networklayer 110. Specifically, optical node 125 a may use GMPLS signaling todetermine a path from network layer interface 115 a, through secondlayer network 110 and out network layer interface 115 b to router 120 b.

Specifically, optical node 125 a may send out or flood a plurality ofsignaling messages 422 a and 422 b, such as GMPLS signaling messages, tocommunicate with the other optical nodes in second network layer 110 inan attempt to find a path through second network layer 110 that canfulfill the bandwidth request made in message 310. Upon determining asuccessful path through the second network layer 110, communicationtunnel 425 is established between router 120 a and router 120 b, andcommunication is commenced through second network layer 110.

As with the example of FIG. 3, PCE 130 will continue monitor thecommunications between router 120 a and 120 b, dynamically changing thebandwidth allocations for communication tunnels 305 and 425, as needed.

With reference now made to FIG. 5, depicted therein is another examplenetwork environment 500 which is configured to provide on-demandbandwidth between network devices. Network environment 500 is similar tonetwork environment 100 of FIGS. 1, 3 and 4, and therefore, likereference numerals have been used to reference to like components.Network environment 500 differs from the previous examples in that anadditional router, router 120 f, is included in network environment 500,as have been network links 122 e and 122 f Furthermore, instead ofcommunicating with router 120 b, router 120 a communicates with router120 f through tunnel 505. As with the previous examples, thecommunications between router 120 a and 120 f initially require 7gigabytes of bandwidth. Subsequently, a request 510 is sent from router120 f to stateful PCE 130 requesting an additional 8 gigabytes ofbandwidth, a request that cannot be fulfilled through 10 gigabyte links122 a and 122 e as they are already providing 7 gigabytes of bandwidththrough tunnel 505. Accordingly, PCE 130 will establish an on-demandtunnel through second network layer 110.

Unlike the example of FIG. 3, router 120 f is not located on the ingressor egress to second layer network 110. Furthermore, when message 515 issent to router 120 f to establish a bandwidth on demand tunnel, message515 does not include an explicit path for the new on-demand tunnel. Thisis because security and/or confidentiality concerns may prevent PCE 130from explicitly defining the entire path through second layer network110. Accordingly, included in message 515 is an ERO which defines thepath from router 120 f to router 120 c, and one or more path keys whichmay be used by router 120 c and other subsequent nodes to determine therest of the path through the first network layer 105 and the secondnetwork layer 110. A path key is used in place of a segment of the pathof an LSP when the LSP is signaled, when the path of the LSP is reportedby signaling, or when the LSP's path is generated by a PCE. This allowsthe exact path of the LSP to remain confidential through thesubstitution of confidential path segments (CPSs) by these path keys.Once received by the appropriate node, the node can translate the CPSinto the next hop in the path.

Accordingly, message 515 may include an ERO which defines the hop fromrouter 120 f to 120 c, and also includes three CPSs, one CPS for the hopfrom router 120 c to optical node 125 a, one CPS for the hop fromoptical node 125 c to optical node 125 a, and one CPS for the hop fromoptical node 125 a to router 120 a, each of which includes a path key.Furthermore, the portion of the ERO defining the path to router 120 cmay be “loose,” meaning it is not explicitly defined by the ERO, and therouting devices along the path may determine the specific hops necessaryto reach router 120 c.

Once received at router 120 c, the corresponding path key in the CPS inthe LSP will be translated by node 120 c. Accordingly, the LSP will besignaled to optical node 125C where the next path key in the next CPSwill be translated. This process will continue until the LSP has beensignaled to router 120 a, at which time bandwidth on-demandcommunication tunnel 520 is established.

As with the examples of FIGS. 3 and 4, PCE 130 will continue monitor thecommunications between router 120 a and 120 b, dynamically changing thebandwidth allocations for communication tunnels 505 and 520, as needed.

Turning now to FIG. 6, depicted therein is an example block diagram of anetwork device, e.g., stateful network device 130 (e.g. a PCE),configured to perform the techniques described herein in connection withFIGS. 1-5. The stateful network device 130 comprises one or more networkinterface units 610 (e.g., network interface cards) to enablecommunication over a network, processor(s) 620, bus 630, and memory 640.The memory 640 contains software instructions for operating system 645and bandwidth on-demand functional unit 135.

Memory 640 may comprise read only memory (ROM), random access memory(RAM), magnetic disk storage media devices, optical storage mediadevices, flash memory devices, electrical, optical, or otherphysical/tangible (e.g., non-transitory) memory storage devices. Theprocessor 620 is, for example, a microprocessor or microcontroller thatexecutes instructions for stateful network device 130. Thus, in general,the memory 640 may comprise one or more tangible (non-transitory)computer readable storage media (e.g., a memory device) encoded withsoftware comprising computer executable instructions and when thesoftware is executed (by the processor 620), and in particular bandwidthon-demand functional unit 135, it is operable to perform the operationsdescribed herein in connection with FIGS. 1-5. Specifically, bandwidthon-demand functional unit 135 includes instructions that allow processor620 to generate LSPs for bandwidth on-demand communication tunnels asdescribed herein.

The techniques taught herein provide substantial benefits to multilayernetwork configurations. For example, the use of a stateful PCE is one ofthe components of the Software Defined Networks (SDN). Accordingly, thetechniques taught herein are easily deployed within SDN networks.Furthermore, the techniques taught herein build on the existing PCE andRSVP-TE framework.

Furthermore, the techniques described herein address important problemsfaced by service providers, such as how to efficiently use and sharespare bandwidth in the optical network and create services in anon-demand basis. By implementing the techniques described herein,networks with fewer resources can provide the same level of availabilityas networks with higher cost infrastructures.

The above description is intended by way of example only.

What is claimed is:
 1. A method comprising: monitoring, by a statefulpath computation element, bandwidth usage of an existing communicationtunnel between a first network device and a second network device,wherein the existing communication tunnel operates in a first networklayer; determining, by the stateful path computation element, thatadditional bandwidth is required for communication between the firstnetwork device and the second network device; determining, by thestateful path computation element, that providing the additionalbandwidth would exceed available bandwidth of the existing communicationtunnel; and establishing the additional bandwidth through an additionalcommunication tunnel between the first network device and the secondnetwork device, operating in a second network layer in parallel with theexisting communication tunnel, via a Generalized Multiprotocol LabelSwitching (GMPLS) label-switched path, wherein establishing the GMPLSlabel-switched path comprises sending a first GMPLS signaling message toa third network device in the first network layer that is located at aningress point in the second network layer.
 2. The method of claim 1,further comprising monitoring, by the stateful path computation element,bandwidth usage within the second network layer, and whereinestablishing the additional bandwidth through the additionalcommunication tunnel comprises sending a second GMPLS signaling messageto a fourth network device in the first network layer that is located atan egress point in the second network layer.
 3. The method of claim 2,wherein the first GMPLS signaling message indicates a path of theadditional communication tunnel from the third network device to thefourth network device in the second network layer.
 4. The method ofclaim 3, wherein the second GMPLS signaling message indicates the pathof the additional communication tunnel from the fourth network device tothe third network device in the second network layer.
 5. The method ofclaim 4, wherein the first GMPLS signaling message comprises alabel-switched path from the third network device to the fourth networkdevice in the second network layer.
 6. The method of claim 4, whereinthe second GMPLS signaling message comprises a label-switched path fromthe fourth network device to the third network device in the secondnetwork layer.
 7. The method of claim 1, wherein the first GMPLSsignaling message is configured to cause the third network device tosend at least one message in the second network layer to determine apath through the second network layer.
 8. The method of claim 7, whereinthe first GMPLS signaling message contains an address in the secondnetwork layer of a fourth network device, wherein the fourth networkdevice is located in the first network layer at an egress point in thesecond network layer.
 9. An apparatus comprising: a network interfaceunit configured to enable network communications; and a processorcoupled to the network interface unit and the memory, wherein theprocessor is configured to: monitor bandwidth usage of an existingcommunication tunnel between a first network device and a second networkdevice, wherein the existing communication tunnel operates in a firstnetwork layer; determine that additional bandwidth is required forcommunication between the first network device and the second networkdevice; determine that providing the additional bandwidth would exceedavailable bandwidth of the existing communication tunnel; and establishthe additional bandwidth through an additional communication tunnelbetween the first network device and the second network device,operating in a second network layer in parallel with the existingcommunication tunnel, via a Generalized Multiprotocol Label Switching(GMPLS) label-switched path, wherein to establish the GMPLSlabel-switched path a first GMPLS signaling message is sent, via thenetwork interface unit, to a third network device in the first networklayer that is located at an ingress point in the second network layer.10. The apparatus of claim 9, wherein the processor is furtherconfigured to: monitor bandwidth usage within the second network layer;and establish the additional bandwidth through the additionalcommunication tunnel by sending a second GMPLS signaling message to afourth network device in the first network layer that is located at anegress point in the second network layer.
 11. The apparatus of claim 10,wherein the first GMPLS signaling message comprises a label-switchedpath from the third network device to the fourth network device in thesecond network layer.
 12. The apparatus of claim 10, wherein the secondGMPLS signaling message comprises a label-switched path from the fourthnetwork device to the third network device in the second network layer.13. The apparatus of claim 9, wherein the first GMPLS signaling messageis configured to cause the third network device to send at least onemessage through the second network layer to determine a path in thesecond network layer.
 14. The apparatus of claim 13, wherein the firstGMPLS signaling message contains an address in the second network layerof a fourth network device, wherein the fourth network device is locatedin the first network layer at an egress point in the second networklayer.
 15. A tangible, non-transitory computer readable mediumcomprising instructions that when executed by a processor cause theprocessor to: monitor, by a stateful path computation element, bandwidthusage of an existing communication tunnel between a first network deviceand a second network device, wherein the existing communication tunneloperates within a first network layer; determine, by the stateful pathcomputation element, that additional bandwidth is required forcommunication between the first network device and the second networkdevice; determine, by the stateful path computation element, thatproviding the additional bandwidth would exceed available bandwidth ofthe existing communication tunnel; and establish the additionalbandwidth through an additional communication tunnel between the firstnetwork device and the second network device, operating in a secondnetwork layer in parallel with the existing communication tunnel, via aGeneralized Multiprotocol Label Switching (GMPLS) label-switched path,wherein to establish the GMPLS label-switched path a first GMPLSsignaling message is sent to a third network device in the first networklayer that is located at an ingress point in the second network layer.16. The tangible, non-transitory computer readable medium of claim 15,wherein the instructions further cause the processor to: monitor, by thestateful path computation element, bandwidth usage within the secondnetwork layer; and establish the additional bandwidth through theadditional communication tunnel by sending a second GMPLS signalingmessage to a fourth network device in the first network layer that islocated at an egress point in the second network layer.
 17. Thetangible, non-transitory computer readable medium of claim 16, whereinthe first GMPLS signaling message comprises a label-switched path fromthe third network device to the fourth network device in the secondnetwork layer.
 18. The tangible, non-transitory computer readable mediumof claim 16, wherein the second GMPLS signaling message comprises alabel-switched path from the fourth network device to the third networkdevice in the second network layer.
 19. The tangible, non-transitorycomputer readable medium of claim 15, wherein the first GMPLS signalingmessage is configured to cause the third network device to send at leastone message through the second network layer to determine a path fromthe second network layer.
 20. The tangible, non-transitory computerreadable medium of claim 19, wherein the first GMPLS signaling messagecontains an address in the second network layer of a fourth networkdevice, wherein the fourth network device is located at an egress pointin the second network layer.